Information recording medium having double-layer structure, and information reproducing apparatus and information recording and reproducing apparatus utilizing information recording medium having double-layer structure

ABSTRACT

An information recording medium comprises a double-layer structure comprised of a light transmitting layer for transmitting light and a light reflecting layer for reflecting light, The light transmitting layer has a data mark which comprises a unit of information to be reproduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national state application of copendingInternational Application Ser. No. PCT/JP99/04892, filed Sep. 8, 1999,and claiming a priority date of Sep. 17, 1998, and published in anon-English language.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a medium for recording informationreproducible by utilizing near-field light and an informationreproducing apparatus and an information recording and reproducingapparatus for reproducing information recorded in the informationrecording medium at a high density, particularly to an informationrecording medium and an information reproducing apparatus capable ofproviding a reproduced signal having a large intensity and aninformation recording and reproducing apparatus having high reliabilityand capable of carrying out high-speed recording.

2. Background Information

A number of present information reproducing apparatus carry outinformation reproduction on a magnetic disk or an optical disk as aninformation recording medium. In particular, a CD, which is one ofoptical disks enabling information recording at a high density and massproduction at low cost, is widely utilized as a medium for recordinginformation having a large capacity. The CD is formed with pits having asize of a wavelength of laser beam used in reproduction and a depth ofabout a quarter of the wavelength on its surface to thereby enable areading operation utilizing an interference phenomenon of light.

In reading recorded information from an optical disk represented by CD,generally, there is utilized a lens optical system used in an opticalmicroscope. Hence, when information recording density is increased byreducing the size or the track pitch of a pit, due to a problem of adiffraction limit of light, the system runs into a wall that a spot sizeof laser beam cannot be made a half wavelength or smaller and aninformation recording unit cannot be constituted by a size smaller thanthe wavelength of laser beam.

Further, not only in an optical disk but also in a magneto-optical diskrecording information by a magneto-optical recording system and a phasechange recording system, recording and reproduction of information at ahigh density is realized by a very small spot of laser beam andtherefore, the information recording density is restricted by thediameter of the spot provided by focusing laser beam.

Hence, in order to break though the restriction by the diffractionlimit, there has been proposed an information reproducing apparatususing an optical head provided with a very small aperture having adiameter equal to or smaller than the wavelength of laser beam utilizedfor reproduction, for example, about 1/10 of the wavelength andutilizing near-field light (including both of near-field light andfar-field light) generated at the very small aperture portion.

Inherently, there is provided a near-field microscope using a probehaving the above-described very small aperture as an apparatus ofutilizing near-field light and the near-field microscope is utilized forobservation of a very small surface structure of a sample. As one ofnear-field light utilizing systems in a near-field microscope, there isprovided a system (illumination mode) in which a distance between a verysmall aperture of a probe and a surface of a sample is reduced to adegree of a diameter of the very small aperture of the probe andpropagated light is introduced via the probe and toward the very smallaperture of the probe, thereby, near-field light is generated at thevery small aperture. In this case, scattered light produced by aninteraction between the generated near-field light and the surface ofthe sample, is detected by a scattered light detecting system by beingaccompanied by intensity or phase reflected with a fine structure of thesurf ace of the sample and there is enabled observation having a highresolution which cannot be realized by a conventional opticalmicroscope.

Further, as another system of a near-field microscope utilizingnear-field light, there is provided a system in which near-field lightis localized at the surface of a sample by irradiating propagated lighttoward a sample and a very small aperture of a probe is made proximateto the surface of the sample up to a degree of the diameter of the verysmall aperture of the probe (collection mode). In this case, scatteredlight produced by interaction between the localized near-field light andthe very small aperture of the probe, is introduced to a scattered lightdetecting system via the very small aperture of the probe by beingaccompanied by the intensity or phase reflected with a fine structure ofthe surface of the sample to thereby achieve observation having a highresolution.

Information reproducing apparatus utilizing the above-describednear-field light, utilizes these observation systems in the near-fieldmicroscope and by utilizing the near-field light, informationreproduction of an information recording medium recorded withinformation at a higher density can be carried out.

In such an information reproducing apparatus, as a probe for reproducinginformation, there is particularly proposed use of a planer probewithout a sharpened front end. FIG. 14 is a view showing a conventionalplaner probe utilizing near-field light and an information recordingmedium. In FIG. 14, a planer probe 101 is formed with an aperture havingan inverse pyramid structure on a planer substrate and particularly, anapex portion of the aperture is penetrated by a very small aperture 102having a diameter of several tens nanometers. According to the planerprobe 101, near-field light 107 is generated at a vicinity of the verysmall aperture 102 by irradiating laser beam 106 toward the very smallaperture 102.

The near-field light 107 is scattered by a data mark 105 particularlyshowing strong interaction between the near-field light and the datamark and produces propagated light 108 at an information recordingmedium 104. The propagated light 108 is introduced to a light receivingelement 103 provided at a vicinity of the very small aperture 102 of theplaner probe 101 and is detected as a reproduced signal.

As described above, the planer probe is constructed by a constitution inwhich both of the very small aperture 102 for generating the near-fieldlight 107 and the light receiving element 103 for detecting thepropagated light 108 scattered from the data mark 105, are arranged on aside of a surface of the information recording medium 104 (reflectionmode) and therefore, downsizing of an information reproducing apparatuscan be achieved, further, the planer probe can be formed by using thesemiconductor fabrication technology and accordingly, mass productionhaving high reproducibility is realized and the planer probe ispertinently used as an optical head of the information reproducingapparatus utilizing the near-field light.

Further, high density information recording can be carried out also bychanging a state, for example, a crystal state of the surface of theinformation recording medium by interaction between the near-field lightgenerated from the probe and the information recording medium.

However, in using the planer probe 101, in order to provide thepropagated light 108 scattered from the data mark 105, since thepropagated light 108 is defined as light having a wavelength of several100 nm, it is necessary to make a distance “a” from the data mark 105 orthe very small aperture 106 to the light receiving element 103 equal toor larger than the wavelength. In this case, a clearance “d” between thevery small aperture 102 and the information recording medium 104 isgenerally provided with a value equal to or smaller than 100 nm in orderto achieve sufficiently large interaction between the near-field light107 generated at the very small aperture 102 and the data mark 105 onthe information recording medium 104. Therefore, in the clearance “d”,the propagated light 108 is detected only at a location separated fromthe data mark 105 by at least several 100 nm or more in a direction inparallel with the surface of the information recording medium 104.

Generally, since the near-field light 107 is introduced from right abovethe data mark 105, an essential intensity distribution of the propagatedlight 108 produced by being scattered by the data mark 105, indicates asmall value with respect to a component of the propagated light in thedirection in parallel with the surface of the information recordingmedium 104. Further, since the clearance “d” is provided with asufficiently small value, a light amount of the propagated light 108cannot be provided sufficiently.

Further, as an information reproducing apparatus, there can be selecteda constitution in which the substrate of the information recordingmedium 104 is formed by a light transmitting member and the propagatedlight 108 scattered from the data mark 105 is detected at a rear face ofthe information recording medium 104 (transmission mode), however, it isnecessary to install a light receiving element on the rear face side ofthe information recording medium 104, which results in large-sizedformation of the apparatus.

Further, recording can be carried out also by generating near-fieldlight by using the above-described planer type near-field optical headand by changing, for example, a crystal state of a surface of aninformation recording medium as an information recording apparatus. Inthis case, it is necessary to provide some assisting energy to thesurface of the information recording medium since the intensity of thenear-field light is very low. This is referred to as assist light. Theassist light is irradiated to the data mark by propagating the assistlight in a direction right reverse to that of the propagated light 108in FIG. 14, which provides energy at a level which is slightly smallerthan the threshold of energy necessary for changing the state of thesurface of the information recording medium. By adding energy of thenear-field light irradiated from the near-filed optical head to theenergy of the assist light, there is provided the energy exceeding theabove-described threshold and the state of the surface of theinformation recording medium is changed, which constitutes recording ofinformation.

In order to carry out information recording by such a method, it isnecessary to irradiate assist light to the data mark stably withsufficient intensity, however, similar to the propagated light in theinformation reproducing apparatus, there poses a problem that a spacefor propagating the assist light is insufficient. That is, it isnecessary to make the near-field optical head and the surface of theinformation recording medium proximate to each other such that the bothcan carry out interaction by the near-field light and it is difficultthat the assist light which is propagated light invades the smallclearance. Therefore, the assist light having sufficient intensitycannot reach the data mark and the data mark cannot be provided withenergy necessary for recording even by adding the near-field light fromthe near-field optical head.

In view of the above-described problems, it is an object of theinvention to provide an information recording medium capable ofproviding a reproduced signal having a sufficiently large intensity ofinformation recorded at a high density, an information reproducingapparatus achieving downsized formation by the information recordingmedium and an information recording and reproducing apparatus havinghigh speed and high reliability.

SUMMARY OF THE INVENTION

In order to achieve the above-described object, a first informationrecording medium according to the invention is characterized in that inan information recording medium formed with information reproduced by areproducing probe provided with a very small aperture for generatingnear-field light on a surface of the medium wherein the informationrecording medium comprises a two layer structure of a light transmittinglayer for transmitting light and a light reflecting layer for reflectinglight and a data mark constituting a unit of the information is formedon the light transmitting layer.

According to the invention, the first information recording mediumcomprises the two layer structure of the light transmitting layercomprising the light transmitting member and the light reflecting layercomprising the light reflecting member and the data mark is formed abovethe light reflecting layer and accordingly, the propagated lightgenerated by the interaction between the near-field light and the datamark can be reflected by the light reflecting layer via the lighttransmitting layer and can be emitted from the surface of theinformation recording medium and a sufficiently large amount of thepropagated light can be provided at the surface of the informationrecording medium at a position remote from the data mark.

Further, a second information recording medium according to theinvention in accordance with the first information recording mediumaccording to the invention is characterized in that an interface betweenthe light transmitting layer and the light reflecting layer is inclinedin one direction.

According to the invention, the second information recording mediumcomprises the two layer structure of the light transmitting layercomprising the light transmitting member and the light reflecting layercomprising the light reflecting member, the interface between the lighttransmitting layer and the light reflecting layer is inclined in onedirection, the data mark is formed on the light transmitting layer andaccordingly, the propagated light generated by the interaction betweenthe near-field light and the data mark can be strongly reflected in theone direction at the light reflecting layer via the light transmittinglayer and can be emitted from the surface of the light recording mediumand a sufficient amount of the propagated light can be provided at thesurface of the information recording medium at a position remote fromthe data mark on the side of the inclined face of the light reflectinglayer 1.

Further, a third information recording medium according to the inventionin accordance with the first information recording medium according tothe invention is characterized in that a surface of the light reflectinglayer constituting an interface between the light transmitting layer andthe light reflecting layer, is formed in a shape of reflecting lightincident on the light reflecting layer to a specific area.

According to the invention, the third information recording mediumcomprises the two layer structure of the light transmitting layercomprising the light transmitting member and the light reflecting layercomprising the light reflecting member, the surface of light reflectinglayer is formed in the shape achieving reflection of light to thespecific area, the data mark 4 is formed on the light transmitting layerand accordingly, the propagated light generated by the interactionbetween the near-field light and the data mark, can pass the lighttransmitting layer, can be strongly reflected to the specific area atthe light reflecting layer, can be emitted from the surface of theinformation recording medium and a sufficient amount of the propagatedlight can be provided at the specific area at a position remote from thedata mark.

Further, a fourth information recording medium according to theinvention in accordance with the third information recording apparatusaccording to the invention is characterized in that the shapeconstitutes a diffraction grating.

According to the invention, the fourth information recording mediumcomprises the two layer structure of the light transmitting layercomprising the light transmitting member and the light reflecting layercomprising the light reflecting member, the diffraction grating isformed at the surface of the light reflecting layer, the data mark isformed on the light transmitting layer and accordingly, the propagatedlight generated by the interaction of the near-field light and the datamark can pass through the light transmitting layer, can be stronglyreflected to the specific area determined by the diffraction grating atthe light reflecting layer and can be emitted from the surface of theinformation recording medium and a sufficient amount of the propagatedlight can be provided at the specific area at a position remote from thedata mark.

Further, a first information reproducing apparatus according to theinvention is characterized in that in an information reproducingapparatus for reproducing information by a reproducing probe providedwith a very small aperture for generating near-field light, theinformation reproducing apparatus comprising an information recordingmedium comprising a two layer structure of a light transmitting layerfor transmitting light and a light reflecting layer for reflecting lightand formed with a data mark constituting a unit of the information onthe light transmitting layer, and light detecting means for detectingpropagated light generated by an interaction between the near-fieldlight and the data mark and outputting a detected signal.

According to the invention, there is used the information recordingmedium comprising the two layer structure of the light transmittinglayer comprising the light transmitting member and the light reflectinglayer comprising the light reflecting member and formed with the datamark on the light reflecting layer, the propagated light provided by theinformation recording medium is received by the light detecting means, areproduced signal having sufficiently large intensity indicatingpresence or absence of the data mark can be provided and accordingly,there can be realized downsized formation of the apparatus in the caseof adopting the illumination mode and a transmission mode constituting asystem of information reproduction utilizing near-field light and therecan be reproduced stable information having high reliability by thereproduced signal having the sufficiently large intensity.

Further, a second information reproducing apparatus according to theinvention is characterized in that in an information reproducingapparatus for reproducing information by a reproducing probe providedwith a very small aperture for guiding out propagated light by aninteraction with near-field light, the information reproducing apparatuscomprising an information recording medium comprising a two layerstructure of a light transmitting layer for transmitting light and alight reflecting layer for reflecting light and formed with a data markconstituting a unit of the information on the light transmitting layer,and light irradiating means for irradiating irradiation light forgenerating the near-field light at the data mark to the informationrecording medium.

According to the invention, there is used the information recordingmedium comprising the two layer structure of the light transmittinglayer comprising the light transmitting member and the light reflectinglayer comprising the light reflecting member and formed with the datamark above the light reflecting layer, the propagated light provided bythe information recording medium is received by the light detectingmeans, a reproduced signal having a sufficiently large intensityindicating presence or absence of the data mark can be provided andaccordingly, there can be realized downsized formation of the apparatusin the case of adopting the collection mode and the transmission modeconstituting the system of information reproduction utilizing near-fieldlight and there can be reproduced stable information having highreliability by the reproduced signal having the sufficiently largeintensity.

Further, a third information reproducing apparatus according to theinvention is characterized in that in an information reproducingapparatus for reproducing information by a reproducing probe providedwith a very small aperture for generating near-field light, theinformation reproducing apparatus comprising an information recordingmedium comprising a two layer structure of a light transmitting layerfor transmitting light and a light reflecting layer for reflecting lightand formed with a data mark constituting a unit of the information onthe light transmitting layer, first and second light detecting means foroutputting detected signals by detecting propagated light generated byan interaction between the near-field light and the data mark andarranged on left and right sides of the very small aperture, differencecalculating means for calculating a difference between a first detectedsignal outputted from the first light detecting means and a seconddetected signal outputted from the second light detecting means andoutputting a difference signal, reproducing probe position controllingmeans for controlling a position of the reproducing probe in accordancewith the difference signal, and reproduced signal generating means forgenerating a reproduced signal by calculating to add the first detectedsignal and the second detected signal.

According to the invention, there is used the information recordingmedium comprising the two layer structure of the light transmittinglayer comprising the light transmitting member and the light reflectinglayer comprising the light reflecting member and formed with the datamark above the light reflecting layer, the propagated light provided bythe information recording medium can be detected in two directionrelative to the very small aperture of the reproducing probe and therecan be carried out tracking control of the reproducing probe by thedifference between the detected two detected signals. Further, thenear-field light generated at the very small aperture of the reproducingprobe is utilized as a signal for tracking control and therefore, therecan be carried out the tracking control having high accuracy with highpositional resolution.

Further, a fourth information reproducing apparatus according to theinvention in accordance with any one of the first through the thirdinformation reproducing apparatus according to the invention, ischaracterized in that the reproducing probe is a planer probe comprisinga planer substrate formed with a hole in a shape of an inverse conepenetrated such that a top portion thereof constitutes the very smallaperture and arranged with the light detecting means or the lightirradiating means at the planer substrate.

According to the invention, as the reproducing probe, there is adoptedthe planer probe provided with the light detecting means or the lightirradiating means and accordingly, further compact apparatusconstitution is achieved. Further, the planer probe can be fabricated byusing the semiconductor fabrication technology and accordingly, massproduction having high reproducibility can be carried out.

Further, a fifth information reproducing apparatus according to theinvention in accordance with the fourth information reproducingapparatus according to the invention, is characterized in that thereproducing probe carries out reproduction by a state of being inclinedrelative to a surface of the information recording medium.

According to the invention, the propagated light provided by theinformation recording medium comprising the two layer structure of thelight transmitting layer and the light reflecting layer, is received bythe light detecting means of the planer probe arranged to incline suchthat the clearance between the planer probe and the surface of theinformation recording medium becomes sufficiently large, there can beprovided the reproduced signal having sufficiently large intensityindicating presence or absence of the data mark and accordingly, thereis realized downsized formation of the apparatus in the case of adoptingthe transmission mode constituting one of the system of informationreproduction utilizing near-field light, further, there can bereproduced stable information having high reliability by the reproducesignal having the sufficiently large intensity.

Further, a sixth information reproducing apparatus according to theinvention in accordance with any one of the first through the thirdinformation reproducing apparatus according to the invention, ischaracterized in that the reproducing probe comprises an optical fiber afront end of which is provided with the very small aperture.

According to the invention, there can be utilized the probe of theoptical fiber type used in a conventional near-field microscope as thereproducing probe and accordingly, accumulated technology of thenear-field microscope is effectively applicable to the informationreproducing apparatus.

Further, a seventh information reproducing apparatus according to theinvention in accordance with any one of the first through the thirdinformation reproducing apparatus according to the invention, ischaracterized in that the reproducing probe is a probe of a cantilevertype provided with the very small aperture at a projected portionthereof.

According to the invention, there can be utilized the probe of thecantilever type used in a conventional near-field microscope as thereproducing probe and accordingly, accumulated technology of thenear-field microscope is effectively applicable to the informationreproducing apparatus.

Further, a first information recording and reproducing apparatusaccording to the invention is characterized in that in an informationrecording and reproducing apparatus in which a recording and reproducingprobe provided with a very small aperture for generating near-fieldlight records and reproduces information to and from an informationrecording medium by carrying out an interaction between the recordingand reproducing probe and the information recording medium via thenear-field light wherein the information recording medium comprises atwo layer structure of a light transmitting layer for transmitting lightand a light reflecting layer for reflecting light and formed with a datamark constituting a unit of the information on the light transmittinglayer, the information recording and reproducing apparatus comprisingnear-field light generating light irradiating means for irradiatingirradiation light for generating the near-field light to the recordingand reproducing probe, and propagated light irradiating means forirradiating light to the light reflecting layer such that the light isirradiated to an area at which the near-field light on the lighttransmitting layer carries out the interaction.

According to the invention, the first information recording andreproducing apparatus comprises the light transmitting layer comprisingthe light transmitting member and the light reflecting layer comprisingthe light reflecting member and formed with the data mark above thelight reflecting layer and accordingly, the data mark can be irradiatednot only by the near-field light from the probe but by the light fromthe light reflecting layer and larger energy can be provided by the datamark.

Further, according to a second information recording and reproducingapparatus according to the invention in accordance with the firstinformation recording and reproducing apparatus according to theinvention, is characterized in that the light irradiated to the lightreflecting layer is provided with an intensity and a wavelength forassisting the near-field light for recording the information.

According to the invention, energy necessary for information recordingcan be provided not only by the near-field light from the probe but alsofrom assist light from the light reflecting layer and by changing astate of the surface of the information recording medium by controllingvery weak near-field light, recording having high reliability can becarried out at high speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an outline constitution of aninformation reproducing apparatus according to Embodiment 1 of theinvention.

FIG. 2 is a view for explaining in details, a planer probe and aninformation recording medium of the information reproducing apparatusaccording to Embodiment 1 of the invention.

FIG. 3 is a view for explaining in details, a planer probe and aninformation recording medium of an information reproducing apparatusaccording to Embodiment 2 of the invention.

FIG. 4 is a view for explaining in details, a planer probe and aninformation recording medium of an information reproducing apparatusaccording to Embodiment 3 of the invention.

FIG. 5 is a view for explaining in details, a planer probe and aninformation recording medium of an information reproducing apparatusaccording to Embodiment 4 of the invention.

FIG. 6 is a view for explaining in details, a planer probe and aninformation recording medium of an information reproducing apparatusaccording to Embodiment 5 of the invention.

FIG. 7 is a view for explaining in details, a planer probe and aninformation recording-medium of an information reproducing apparatusaccording to Embodiment 6 of the invention.

FIG. 8 is a view for explaining in details, a planer probe and aninformation recording medium of an information reproducing apparatusaccording to Embodiment 7 of the invention.

FIG. 9 is a block diagram showing an outline constitution of theinformation reproducing apparatus according to Embodiment 7 of theinvention.

FIG. 10 is a view for explaining in details, a planer probe and aninformation recording medium of an information reproducing apparatusaccording to Embodiment 8 of the invention.

FIG. 11 is a view for explaining in details, a planer probe and aninformation recording medium of other example of the informationreproducing apparatus according to Embodiment 8 of the invention.

FIG. 12 is a view for explaining in details, a planer probe and aninformation recording medium of an information reproducing apparatusaccording to Embodiment 9 of the invention.

FIG. 13 is a block diagram showing an outline constitution of theinformation reproducing apparatus according to Embodiment 9 of theinvention.

FIG. 14 is a view showing a planer probe and an information recordingmedium of a conventional art utilizing near-field light.

FIG. 15 is an enlarged view showing a head portion of an informationrecording and reproducing apparatus according to Embodiment 10 of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A detailed explanation will be given of embodiments of an informationrecording medium, an information reproducing apparatus and aninformation recording and reproducing apparatus in reference to thedrawings as follows.

(Embodiment 1)

FIG. 1 is a block diagram showing an outline constitution of aninformation reproducing apparatus according to Embodiment 1 of theinvention. In FIG. 1, the information reproducing apparatus according toEmbodiment 1 is provided with a planer probe 1 for generating near-fieldlight, an information recording medium 3 formed with a data mark 4 at ahigh density, light receiving element 6 and 7 for receiving propagatedlight scattered by the data mark 4 and outputting electric signals andan adding circuit 10 for carrying out adding operation by amplifying therespective electric signals outputted from the light receiving elements6 and 7 and outputting a reproduced signal.

FIG. 2 is a view for explaining in details, the planer probe 1 and theinformation recording medium 3. In FIG. 2, the planer probe 1 is formedwith a very small aperture 2 having a size equal to or smaller than awavelength of laser beam 8 introduced from a laser beam source (notillustrated), for example, a diameter of several tens nanometers forgenerating near-field light 5 at the very small aperture 2 byintroducing the laser beam 8.

The near-field light 5 generated at the very small aperture 2 of theplaner probe 1, is scattered by a record mark 4 formed at theinformation recording medium 3 and the scattered light constitutespropagated light 14 which is incident on the light receiving elements 6and 7. In this case, the planer probe 1 as shown by FIG. 2 is formed bya silicon process used in the conventional semiconductor fabricationtechnology and the light receiving elements 6 and 7 comprise photodiodesintegrated on a silicon wafer. Further, although in FIG. 2, in order toreceive a sufficient amount of the propagated light 14, the two lightreceiving elements 6 and 7 are provided at vicinities of the very smallaperture 2 and symmetrically relative to the very small aperture 2,there may be constituted either one of the light receiving elements.

Further, the information recording medium 3 is constructed by a twolayer structure of a light transmitting layer 11 comprising a lighttransmitting member and a light reflecting member 12 comprising a lightreflecting member and the data mark 4 is formed on the lighttransmitting layer 11.

Therefore, most of the propagated light 14 provided by interactionbetween the near-field light 5 generated at the very small aperture 2and the data mark 4, reaches a lower layer of the light reflecting layer12 by passing through the light transmitting layer 11. That is, in thelight transmitting layer 11, scattering of the near-field light by theabove-described transmission mode is achieved. The propagated light 14which has reached the light reflecting layer 12, is reflected by asurface of the light reflecting layer 12, specifically, an interfacebetween the light transmitting layer 11 and the light reflecting layer12, passes through the light transmitting layer 11 again and is emittedfrom the surface of the information recording medium 3.

Thereby, the propagated light 14 scattered at the data mark 4, followsan optical path having a distance at least twice as much as a thicknessof the light transmitting layer 11 and by sufficiently thickening thethickness of the light transmitting layer 11, an amount of thepropagated light 14 emitted from the surface of the informationrecording medium 3 can be increased. That is, an amount of thepropagated light 14 which can be received by the light receivingelements 6 and 7 is also increased and a reproduced signal having largeintensity can be provided.

As has been explained, according to the information recording mediumaccording to Embodiment 1, the information recording medium isconstructed by the two layer structure of the light transmitting layer 1comprising a light transmitting member and the light reflecting layer 12comprising a light reflecting member, the data mark 4 is formed abovethe light reflecting layer 12 and therefore, the propagated light 14scattered at the data mark 4 can be reflected by the light reflectinglayer 12 via the light transmitting layer 11 and can be emitted from thesurface of the information recording medium 3 and a sufficiently largeamount of the propagated light 14 can be provided at a position remotefrom the data mark 4 and above the information recording medium 3.Further, according to the information reproducing apparatus according toEmbodiment 1, the propagated light 14 provided by the above-describedinformation recording medium 3 can be received by the light receivingelements 6 and 7 of the planer probe 1, the reproduced signal having asufficiently large intensity indicating presence or absence of the datamark 4 can be provided and therefore, the downsized formation of theapparatus in the case of adopting the above-described transmission modecan be achieved, further, there can be reproduced stable informationhaving high reliability by the reproduced signal having sufficientlylarge intensity.

(Embodiment 2)

Next, an explanation will be given of an information recording mediumand an information reproducing apparatus according to Embodiment 2. Theinformation reproducing apparatus according to Embodiment 2 differs fromthe information reproducing apparatus according to Embodiment 1 in aconstitution of a planer probe and a constitution of an informationrecording medium. Other apparatus constitution is similar to that inFIG. 1 and accordingly, an explanation thereof will be omitted here.

FIG. 3 is a view for explaining in details, the planer probe 1 and aninformation recording medium 23 of the information reproducing apparatusaccording to Embodiment 2. In FIG. 3, the planer probe 1 differs fromthe planer probe according to Embodiment 1 in providing only the lightreceiving element 6 for receiving the propagated light 14.

Further, although the information recording medium 23 is constructed bya two layer structure of a light transmitting layer 21 comprising alight transmitting member and a light reflecting layer 22 comprising alight reflecting member, as shown by FIG. 3, an interface between thelight transmitting layer 21 and the light reflecting layer 22, isinclined in one direction orthogonal to a reading direction (or scanningdirection) of the planer probe 1 and in parallel with the surface of theinformation recording medium 3.

Therefore, most of the propagated light 14 provided by the interactionbetween the near-field light 5 generated at the very small aperture 2and the data mark 4 passes through the light transmitting layer 21 andreaches a lower layer of the light reflecting layer 22. That is, in thelight transmitting layer 21, scattering of the near-field light by theabove-described transmission mode is achieved. Further, the propagatedlight 14 which has reached the light reflecting layer 22 is stronglyreflected in the direction of the inclined face of the light reflectinglayer 22 at the surface of the light reflecting layer 22, specifically,the interface between the light transmitting layer 21 and the lightreflecting layer 22 passes through the light transmitting layer 21 againand is emitted from the surface of the information recording medium 23.That is, most of the propagated light 14 is emitted from the surface ofthe information recording medium 23 on the side of the inclined face ofthe light reflecting layer 22 relative to the data mark 4.

Thereby, the propagated light 14 scattered by the data mark 4 follows anoptical path having a distance at least twice as much as a thickness ofthe light transmitting layer 21 right below the data mark 4 and bysufficiently thickening the thickness of the light transmitting layer21, an amount of the propagated light 14 emitted from the surface of theinformation recording medium 23 can be increased. Further, since theinterface between the light transmitting layer 21 and the lightreflecting layer 22, specifically, the surface of the light reflectinglayer 22 is inclined, the direction of reflecting the propagated thelight 14 can be determined. That is, the light receiving element 6 ofthe planer probe 1 is arranged on the side of the inclined face of thelight reflecting layer 22 relative to the very small aperture 2 andreceives a sufficient amount of the propagated light 14 and a reproducedsignal having large intensity can be provided.

As has been explained above, according to the information recordingmedium according to Embodiment 2, the information recording medium isconstructed by the two layer structure of the light transmitting layer21 comprising a light transmitting member and the light reflecting layer22 comprising a light reflecting member. Furthermore, the interfacebetween the light transmitting layer 21 and the light reflecting layer22 is inclined in one direction, the data mark 4 is formed on the lighttransmitting layer 21 and accordingly, the propagated light 14 scatteredat the data mark 4 can pass through the light transmitting layer 21, canbe strongly reflected in one direction at the light reflecting layer 22and can be emitted from the surface of the information recording medium23. Thereby, a sufficiently large amount of the propagated light 14 canbe provided at a position remote from the data mark 4 to the side of theinclined face of the light reflecting layer 22 and at the surface of theinformation recording medium 23. Further, according to the informationreproducing apparatus according to Embodiment 2, the propagated light 14provided by the above-described information recording medium 23 isreceived at the light receiving element 6 of the planer probe 1, and areproduced signal having sufficiently large intensity indicatingpresence or absence of the data mark 4 can be provided. Accordingly,downsized formation of the apparatus in the case of adopting theabove-described transmission mode can be utilized. Furthermore, stableinformation having high reliability by the reproduced signal having thesufficiently large intensity can be reproduced.

(Embodiment 3)

Next, an explanation will be given of an information recording mediumand an information reproducing apparatus according to Embodiment 3. Theinformation reproducing apparatus according to claim 3 differs from theinformation reproducing apparatus according to claim 1 only in aconstitution of an information recording medium. Other apparatusconstitution is similar to that in FIG. 1 and accordingly, anexplanation thereof will be omitted here.

FIG. 4 is a view for explaining in details, the planer probe 1 and aninformation recording medium 33. In FIG. 4, the information recordingmedium 33 is constructed by a two layer structure of a lighttransmitting layer 31 comprising a light transmitting member and a lightreflecting member 32 comprising a light reflecting member, particularly,an interface between the light transmitting layer 31 and the lightreflecting layer 32, specifically, the surface of the light reflectinglayer 32, is formed by two recess portions constituting left and rightsymmetry relative to an axis passing through the data mark 4 and along areading direction (or scanning direction) of the planer probe 1.

Further, each of the recess portions is constituted by a shape in whichthe propagated light 14 scattered from the data mark 4 and passingthrough the light transmitting layer 31, is reflected toward a certainspecific area on the information recording medium 33 disposed rightabove the recess portion.

Therefore, most of the propagated light 14 provided by interactionbetween the near-field light 5 generated at the very small aperture 2and the data mark 4, passes through the light transmitting layer 31 andreaches a lower layer of the light reflecting layer 32, reflected towardthe above-described specific areas at the respective recess portions ofthe light reflecting layer 32 and emitted from the surface of theinformation recording medium 33.

Thereby, the propagated light 14 scattered from the data mark 4 followsan optical path having a distance at least twice as much as a thicknessof the light transmitting layer 31 right below the data mark 4, and bysufficiently thickening a thickness of the light transmitting layer 31,an amount of the propagated light 14 emitted from the surface of theinformation recording medium 33 can be increased. Further, the interfacebetween the light transmitting layer 31 and the light reflecting layer32, specifically, the surface of the light reflecting layer 32, isformed by the two recess portions and, accordingly, directions ofreflecting the propagated light 14 can be determined by the respectiverecess portions. That is, the light receiving elements 6 and 7 of theplaner probe 1 are arranged to be disposed at the above-describedspecific areas determined by the respective recess portions in a stateof being proximate to the surface of the information recording medium 33and receive a sufficient amount of the propagated light 14 and canoutput a reproduced signal having large intensity.

As has been explained above, according to the information recordingmedium according to Embodiment 3, the information recording medium isconstructed by the two layer structure of the light transmitting layer31 comprising a light transmitting member and the light reflectingmember 32 comprising a light reflecting member, further, the surface ofthe light reflecting member 32 is formed by the two recess portions, thedata mark 4 is formed on the light transmitting layer 31 andaccordingly, the propagated light 14 scattered at the data mark 4 canstrongly be reflected toward the specific areas determined by therespective specific portions in the light reflecting layer 32 via thelight transmitting layer 31 and can be emitted from the surface of theinformation recording medium 33. Thereby, a sufficiently large amount ofthe propagated light 14 can be provided at the surface of theinformation recording medium 33 at distances from the data mark 4.Further, according to the information reproducing apparatus according toEmbodiment 3, the propagated light 14 provided by the above-describedinformation recording medium 33 is received by the light receivingelements 6 and 7 of the planer probe 1, a reproduced signal havingsufficiently large intensity indicating presence or absence of the datamark 4 can be provided and accordingly, downsized formation of theapparatus in the case of adopting the above-described transmission modecan be used, further stable information having high reliability by thereproduced signal having the sufficiently large intensity can bereproduced.

(Embodiment 4)

Next, an explanation will be given of an information recording mediumand an information reproducing apparatus according to Embodiment 4. Theinformation reproducing apparatus according to Embodiment 4 differs fromthe information reproducing apparatus according to Embodiment 1 only ina constitution of an information recording medium. Other apparatusconstitution is similar to that in FIG. 1 and accordingly, anexplanation thereof will be omitted here.

FIG. 5 is a view for explaining in details, the planer probe 1 and aninformation recording medium 43 of the information reproducing apparatusaccording to Embodiment 4. In FIG. 5, the information recording medium43 is constructed by a two layer structure of a light transmitting layer41 comprising a light transmitting member and a light reflecting layer42 comprising light reflecting member, particularly, a diffractiongrating is formed at an interface between the light transmitting layer41 and the light reflecting layer 42, specifically, the surface of thelight reflecting layer 42.

The diffraction grating on the surface of the light reflecting layer 42is formed such that the propagated light 14 scattered by the data mark 4and passing through the light transmitting layer 41, is reflected towardcertain specific areas above the information recording medium 43. Forexample, as shown by FIG. 5, the specific areas are two areasconstituting left and right symmetry relative to an axis passing throughthe data mark 4 and along a reading direction (or scanning direction) ofthe planer probe 1 above the information recording medium 43.

Therefore, most of the propagated light 14 provided by interactionbetween the near-field light 5 generated at the very small aperture 2and the data mark 4, passes through the light transmitting layer 41 andreaches a lower layer of the light reflecting layer 42, is stronglyreflected toward the above-described specific areas at the diffractiongrating of the light reflecting layer 42 and is emitted from the surfacefrom the information recording medium 43.

Thereby, the propagated light 14 scattered from the data mark 4, followsan optical path having a distance at least twice as much as a thicknessof the light transmitting layer 41 right below the data mark 4 and bysufficiently thickening the thickness of the light transmitting layer41, an amount of the propagated light 14 emitted from the surface of theinformation recording medium 43 can be increased. Further, since thediffraction grating is formed at the surface of the light reflectinglayer 42, the direction of reflecting the propagated light 14 can bedetermined with high accuracy by the diffraction grating. That is, thelight receiving elements 6 and 7 of the planer probe 1 are arranged todispose at the above-described specific areas determined by thediffraction grating in a state in which the planer probe 1 is proximateto the surface of the information recording medium 43 and receives asufficiently large amount of the propagated light 14 and a reproducedsignal having large intensity can be provided.

As has been explained above, according to the information recordingmedium according to Embodiment 4, the information recording medium isconstructed by the two layer structure of the light transmitting layer41 comprising a light transmitting member and the light reflecting layer42 comprising a light reflecting member, the diffraction grating isformed at the surface of the light reflecting layer 42, the data mark 4is formed on the light transmitting layer 41 and accordingly, thepropagated light 14 scattered at the data mark 4, can strongly bereflected toward the specific areas determined by the diffractiongrating at the light reflecting layer 42 via the light transmittinglayer 41 and can be emitted from the surface of the informationrecording medium 43. Thereby, a sufficiently large amount of thepropagated light 14 can be provided at positions remote from the datamark 4 and above the information recording medium 43. Further, accordingto the information reproducing apparatus according to Embodiment 4, thepropagated light 14 provided by the above-described informationrecording medium 43, is received by the light receiving elements 6 and 7of the planer probe 1, the reproduced signal having sufficiently largeintensity indicating presence or absence of the data mark 4 can beprovided and accordingly, downsized formation of the apparatus in thecase of adopting the above-described transmission mode can be utilized,further, stable information having high reliability by the reproducedsignal having the sufficiently large intensity can be reproduced.

(Embodiment 5)

Next, an explanation will be given of an information recording mediumand an information reproducing apparatus according to Embodiment 5. Theinformation reproducing apparatus according to Embodiment 5 differs fromthe information reproducing apparatus according to Embodiment 1 in theconstitution of the planer probe and arrangement thereof with respect tothe information recording medium. Other apparatus constitution issimilar to that in FIG. 1 and accordingly, an explanation thereof willbe omitted here.

FIG. 6 is a view for explaining in details, the planer probe 1 and theinformation recording medium 3 of the information reproducing apparatusaccording to Embodiment 5. In FIG. 6, the planer probe 1 differs fromthe planer probe according to Embodiment 1 in that only the lightreceiving element 6 is provided for receiving the propagated light 14.Further, the information recording medium 3 is the same as theinformation recording medium explained in Embodiment 1.

A significant characteristic of the information reproducing apparatusaccording to Embodiment 5 resides in that as shown by FIG. 6, the planerprobe 1 is used to incline relative to the surface of the informationrecording medium 3. Particularly, the planer probe 1 is inclined suchthat a distance thereof from the surface of the information recordingmedium 3 becomes larger on a side thereof arranged with the lightreceiving element 6 than a side thereof which is not arranged with thelight receiving element 6.

Therefore, most of the propagated light 14 provided by the interactionbetween the near-field light 5 generated at the very small aperture 2and the data mark 4, passes through the light transmitting layer 11,reaches the light reflecting layer 12 at the lower layer, reflected atthe surface of the light reflecting layer 12, passes through the lighttransmitting layer 11 again and is emitted from the surface of theinformation recording medium 3.

Thereby, the propagated light 14 scattered from the data mark 4, followsan optical path having a distance of at least twice as much as thethickness of the light transmitting layer 11 right below the data mark 4and an amount of the propagated light 14 emitted from the surface of theinformation recording medium 3 can be increased. Further, according tothe planer probe 1, the side arranged with the light receiving element 6is utilized by being inclined such that the clearance between the planerprobe 1 and the surface of the information recording medium 3 becomessufficiently large and accordingly, on the side of the light receivingelement 6, the propagated light 14 which has followed the optical pathwhich is increased by the clearance, is received and a reproduced signalhaving large intensity can be outputted. Therefore, in this case, alarge amount of the propagated light 14 can be detected withoutenlarging the thickness of the light transmitting layer 11.

As has been explained above, according to the information reproducingapparatus according to Embodiment 5, the propagated light 14 provided bythe information recording medium 3 comprising the two layer structure ofthe light transmitting layer 11 and the light reflecting layer 12, isreceived at the light receiving element 6 of the planer probe 1 arrangedto be inclined such that the clearance between the planer probe 1 andthe surface of the information recording medium 3 becomes sufficientlylarge, the reproduced signal having sufficiently large intensityindicating presence or absence of the data mark 4, can be provided andtherefore, there is utilized downsized formation of the apparatus in thecase of adopting the above-described transmission mode, further, stablereproduction of information having high reliability can be carried outby the reproduced signal having sufficiently large intensity.

(Embodiment 6)

Next, an explanation will be given of an information reproducingapparatus according to Embodiment 6. According to the informationreproducing apparatus according to Embodiment 6, in the informationreproducing apparatus according to Embodiments 1 through 5, describedabove, the constitution of the planer probe 1 is changed. Otherapparatus constitution is similar to that in FIG. 1 and accordingly, anexplanation thereof will be omitted here.

FIG. 7 is a view for explaining in details, the planer probe 1 and theinformation recording medium 3 of the information reproducing apparatusaccording to Embodiment 6. In FIG. 7, according to the planer probe 1,the light receiving elements 6 and 7 are arranged on an upper face sideof the planer substrate for receiving the propagated light 14 and therespective light receiving elements receive the propagated light 14introduced from the lower face of the planer substrate via optical waveguide paths 16 and 17 provided to connect to lower portions thereof. Byarranging the light receiving elements 6 and 7 at the upper face of theplaner substrate constituting a base member of the planer probe 1,connection of electric wirings for taking out reproduced signalsoutputted from the respective light receiving elements can befacilitated.

Further, although in FIG. 7, as the information recording medium, thereis shown the information recording medium 3 according to Embodiment 1,there can be used the information recording media 23, 33 and 43explained in Embodiments 2 through 4.

As has been explained above, according to the information reproducingapparatus according to Embodiment 6, in the planer probe 1, the lightreceiving elements 6 and 7 are arranged at the upper face of the planersubstrate, the optical wave guide paths 16 and 17 are provided toconnect to the lower portions of the respective light receiving elementsand accordingly, in addition to effects in the information reproducingapparatus according to Embodiment 1 through 5, connection of electricwirings for taking out reproduced signals outputted from the respectivelight receiving elements can be facilitated.

(Embodiment 7)

Next, an explanation will be given of an information reproducingapparatus according to Embodiment 7. According to the informationreproducing apparatus according to Embodiment 7, in the informationreproducing apparatus according to Embodiment 1 through 4, describedabove, the constitution adopting the illumination mode of introducingthe laser beam 8 toward the very small aperture 2 of the planer probe 1and generating the near-field light 5 at the very small aperture 2, ischanged to a constitution of adopting a collection mode of irradiatingthe laser beam toward the data mark 4 and generating the near-fieldlight 5 on the data mark 4.

FIG. 8 is a view for explaining in details, a planer probe 51 and theinformation recording medium 3 of the information reproducing apparatusaccording to Embodiment 7. In FIG. 8, the planer probe 51 is providedwith light emitting elements 52 and 53 for irradiating laser beam 54symmetrically with respect to the very small aperture 2.

A significant characteristic of the information reproducing apparatusaccording to Embodiment 7 resides in that by adopting the informationrecording medium 3 comprising the two layer structure of the lighttransmitting layer 11 and the light reflecting layer 12, as shown byFIG. 8, generation of the near-field light 5 on the data mark 4 isachieved by irradiating the laser beam 54 from the light emittingelements 52 and 53 toward the light reflecting layer 12 without directlyirradiating the laser beam 54 to the data mark 4. That is, according tothe information reproducing apparatus according to Embodiment 7,reproduction of information by the collection mode and the transmissionmode can be carried out.

FIG. 9 is a block diagram showing an outline constitution of theinformation reproducing apparatus according to Embodiment 7. In FIG. 9,the information reproducing apparatus according to Embodiment 7, isprovided with the above-described planer probe 51, the above-describedinformation recording medium 3, an optical detector 56 for detectingpropagated light derived at the planer probe 51 and an amplifyingcircuit 57 for amplifying an electric signal outputted from the opticaldetector 56 and outputting the signal as a reproduced signal.

According to the operation of the information reproducing apparatusaccording to Embodiment 7, firstly, the laser beam 54 is emitted fromthe light emitting elements 52 and 53 by an irradiation angle achievingirradiation of the laser beam 54 to the data mark 4 finally efficientlyin consideration of reflection at the light reflecting layer 12. Thelaser beam 54 emitted from the light emitting elements 52 and 53 isintroduced to the light transmitting layer 11, reflected at the surfaceof the light reflecting layer 12, specifically, the interface betweenthe light transmitting layer 11 and the light reflecting layer 12 andreaches the rear face portion of the data mark 4 again via thetransmitting layer 11. At the upper face of the data mark 4 irradiatedwith the laser beam 54, the near-field light 5 is generated andintroduced as propagated light 55 by the very small aperture 2 of theplaner probe 1. The propagated light 55 is received by the opticaldetector 56 and is converted into an electric signal. The opticaldetector 56 inputs the provided electric signal to the amplifyingcircuit 57 and at the amplifying circuit 57, the electric signal isamplified and outputted as a reproduced signal indicating presence orabsence of the data mark 4.

Further, although in FIGS. 8 and 9, as the information recording medium,there is shown the information recording medium 3 according toEmbodiment 1, the information recording media 23, 33 and 43 explained inEmbodiments 2 through 4 can be used.

As explained above, according to the information reproducing apparatusaccording to Embodiment 7, by providing the light emitting elements 52and 53 at the planer probe 1 and irradiating the laser beam 54 to theinformation recording medium 3 comprising the two layer structure of thelight transmitting layer 11 and the light reflecting layer 12, laserbeam irradiation from the rear face of the data mark 4 can be achieved,the near-field light 5 can be generated on the data mark 4 andaccordingly, there can be provided the information reproducing apparatusutilizing the near-field light as the collection mode and thetransmission mode.

(Embodiment 8)

Next, an explanation will be given of an information reproducingapparatus according to Embodiment 8. Although in the case of theinformation reproducing apparatus according to Embodiment 7, in theinformation reproducing apparatus according to Embodiment 1 through 7,described above, as the reproducing probe, a planer probe is adopted, inplace thereof, there can be utilized a probe used in a conventionalnear-field microscope. For example, there can be utilized an opticalfiber probe comprising an optical fiber which is provided with a verysmall aperture at a front end thereof and a surface of which is coatedwith a metal, or a cantilever type optical probe having a very smallaperture to which laser beam is introduced via an optical wave guidepath, at a front end thereof.

FIG. 10 is a view for explaining in details, an optical fiber probe 61and the information recording medium 3 of the information reproducingapparatus in the case of adopting an optical fiber probe as areproducing probe. In this case, there are arranged optical detectors 66and 67 along with an optical lens system (not illustrated) at thevicinities of the optical fiber probe 61 and the propagated light 14 isdetected by the optical detectors 66 and 67. Although the optical fiberprobe 61 is generally coated with a light shielding film 63 for reducingtransmission loss of laser beam 68, by presence of the light shieldingfilm 63, the propagated light 14 generated at the vicinity of the verysmall aperture 72 cannot be provided sufficiently and with regard to aconventional information recording medium, a sufficient amount of thepropagated light 14 cannot be generated at the data mark 4 thereby. Thatis, the optical fiber probe 61 also poses a problem similar to that inthe case of adopting the planer probe as a reproducing probe.

However, by adopting the information recording medium 3 according to theinvention as the information recording medium, as has been explained inEmbodiment 1, the propagated light 14 can be increased as a result andreproduced signals having large intensities can be outputted at theoptical detectors 66 and 67.

FIG. 11 is a view for explaining in details, a cantilever type opticalprobe 71 and the information recording medium 3 of an informationreproducing apparatus in the case of adopting the cantilever typeoptical probe as a reproducing probe. In this case,an optical detector76 is provided at a lower face of a lever portion of the optical probe71 of the cantilever type and the propagated light 14 is detected by theoptical detector 76. The cantilever type optical probe 71 is providedwith an optical wave guide path 74 introduced to a very small aperture72 at an inner portion thereof and laser beam 78 is introduced to thevery small aperture 72 via the optical wave guide path 74. Further,similar to the above-described optical probe 61, the cantilever typeoptical probe 71 is coated with a light shielding film 73 for reducingtransmission loss of the laser beam 78, by presence of the lightshielding film 73, the propagated light 14 generated at a vicinity ofthe very small aperture 72 cannot be provided sufficiently and withrespect to a conventional information recording medium, a sufficientamount of the propagated light 14 cannot be generated at the data mark 4thereby. That is, the cantilever type optical probe 71 also poses aproblem similar to that in the case of adopting the planer probe as areproducing probe.

However, also in this case, by adopting the information recording medium3 according to the invention as the information recording medium, as hasbeen explained in Embodiment 1, the propagated light 14 can be increasedas a result and a reproduced signal having a large intensity can beoutputted at the optical detector 76.

Further, although in FIGS. 10 and 11, as the information recordingmedium, there is shown the information recording medium 3 according toEmbodiment 1, the information recording media 23, 33 and 43 explained inEmbodiments 2 through 4 can be used.

As has been explained above, according to the information reproducingapparatus according to Embodiment 8, effects similar to those inEmbodiments 1 through 4 can be achieved also in the case of adopting theoptical fiber probe 61 or the cantilever type optical probe 71 as thereproducing probe.

Further, although in FIGS. 10 and 11, the optical fiber probe 61 or thecantilever type optical probe 71 is respectively shown to carry out theillumination mode, the collection mode is also applicable as explainedin Embodiment 7.

(Embodiment 9)

Next, an explanation will be given of an information reproducingapparatus according to Embodiment 9. According to the informationreproducing apparatus according to Embodiment 9, in the informationreproducing apparatus according to Embodiment 3 and 4, described above,tracking control can further be carried out.

FIG. 12 a view for explaining in details, the planer probe land aninformation recording media 33 of the information reproducing apparatusaccording to Embodiment 9. In FIG. 9, the planer probe 1 is similar tothat explained in Embodiment 1 and there are provided the lightreceiving elements 6 and 7 for receiving the propagated light 14symmetrically with respect to the very small aperture 2.

Further, as explained in Embodiment 3, the information recording medium33 is formed with a light reflecting layer 32 for specifying reflectingpositions of the propagated light 14. Therefore, the light receivingelements 6 and 7 are previously provided at positions equalizing bothlight receiving amounts (generated electric signals) of the propagatedlight 14 when the very small aperture 2 is arranged at a position atwhich a central axis of the very small aperture 2 along a reading trackand a central axis of the data mark 4 coincide with each other. Further,the reading track in this case is a direction of arranging the data mark4 for dealing with data as continuous significant information in theinformation recording medium 3.

Therefore, as shown by FIG. 12, when the very small aperture 2 isarranged at a position at which the central axis along the reading trackand the central axis of the data mark 4 are deviated from each other,there is produced a difference between electric signals generated at thelight receiving elements 6 and 7. It is the characteristic of theinformation reproducing apparatus according to Embodiment 9 to controlto position the planer probe 1 based on a difference signal caused bythe difference.

FIG. 13 is a block diagram showing an outline constitution of aninformation reproducing apparatus according to Embodiment 9. In FIG. 13,the information reproducing apparatus according to Embodiment 9, isprovided with the above-described planer probe 1 for generatingnear-field light, the above-described information recording medium 3,the light receiving elements 6 and 7 for outputting electric signals byreceiving the propagated light 14 scattered by the data mark 4 of theinformation recording medium 3, a difference circuit 81 for outputting adifference signal by calculating a difference between the respectiveelectric signals outputted from the light receiving elements 6 and 7, atracking signal generator 82 for generating and outputting a trackingsignal from the difference signal outputted from the difference circuit81, an actuator 83 for controlling a position of the reproducing probein accordance with the tracking signal outputted from the trackingsignal generator 82 and an adding circuit 80 for generating a reproducedsignal by adding the respective electric signals outputted from thelight receiving elements 6 and 7.

First, as shown by FIG. 12, when the central axis of the very smallaperture 2 in parallel with the reading track is disposed to deviate inthe left direction relative to the reading track of the informationrecording medium 3, the near-field light 5 is scattered further stronglyon the right side of the data mark 4 and the propagated light 14generated thereby is also incident strongly on the recess portion on theleft side of the light reflecting layer 12. That is, the electric signaloutputted at the light receiving element 6 indicates a signal largerthan the electric signal outputted at the light receiving element 7.

As described above, the electric signals are inputted to the differencecircuit 81 and the difference signal is generated there. The magnitudeof the difference signal indicates a degree of deviation between theplaner probe 1 and the reading track and the difference signal isconverted into a tracking signal by being inputted to the trackingsignal generator 82. The tracking signal is a signal for driving theactuator 83 and the actuator 83 controls the position of the planerprobe 1 in accordance with the tracking signal. For example, in thedifference circuit 81, when there is carried out operation ofsubtracting the electric signal outputted from the light receivingelement 7 from the electric signal outputted from the light receivingelement 6, in the state shown by FIG. 12, the difference signaloutputted from the difference circuit 81 indicates a positive value.

Successively, at the tracking signal generator 82, the positivedifference signal is interpreted as a signal for moving the actuator 83to the right and the tracking signal indicating a movement directionthereof and a movement amount in accordance with the magnitude of thedifference signal is outputted to the actuator 83. That is, the trackingsignal generator 82 generates an actuator drive signal for correctingthe deviation between the planer probe 1 and the reading track. Theactuator 83 moves the planer probe 1 in accordance with the trackingsignal outputted from the tracking signal generator 82 and makes thecentral axis of the very small aperture 2 of the planer probe 1 coincidewith the reading track. That is, the tracking control is carried out tothe right direction.

Further, although in FIG. 12, there is shown the case in which theplaner probe 1 is disposed in the left direction relative to the readingtrack (central axis of the data mark 4), when the planer probe 1 isdisposed to deviate in the right direction relative to the readingtrack, operation reverse to the above-described is carried out. That is,in this case, the tracking control is carried out in the left direction.

Further, in parallel with the above-described tracking processing, theelectric signal outputted at the light receiving element 6 and theelectric signal outputted at the light receiving element 7, are inputtedto the adding circuit 80, subjected to the adding operation andoutputted as the reproduced signal. Thereby, there is detected presenceor absence of the data mark 4 right below the very small aperture 2.

As has been explained above, according to the information reproducingapparatus according to Embodiment 9, the propagated light 14 providedfrom the data mark 4 of the above-described information recording medium3 can be detected in two directions symmetrical with respect to the verysmall aperture 2 of the planer probe 1 and the tracking control of theplaner probe 1 can be carried out from the difference of the twodetected electric signals. Further, the near-field light generated atthe very small aperture of the planer probe 1 is utilized as the signalfor the tracking control and accordingly, there is achieved the trackingcontrol having high accuracy with high positional resolution.

Further, although in FIG. 12, as the information recording medium, thereis shown the information recording medium 33 explained in Embodiment 3,similar operation and effect can be achieved also by using theinformation recording medium 43 explained in Embodiment 4. Further, inplace of the planer probe 1, the planer probe 1 shown in Embodiment 6and the optical fiber probe 61 or the cantilever type optical probe 71shown in Embodiment 8 can also be used.

(Embodiment 10)

FIG. 15 shows an enlarged view of a head portion of an informationrecording and reproducing apparatus according to Embodiment 10. Althougha structure thereof is similar to that in the planer probe and theinformation recording medium shown in FIG. 2, a difference therebetweenresides in that light emitting elements 116 and 117 are used in place ofthe light receiving elements 6 and 7 and that propagation directions ofthe propagated light 121 are reversed. A planer probe 111 is formed witha very small aperture 112 having a size equal to or smaller than awavelength of laser beam 118 introduced from a laser light source, notillustrated, for example, a diameter of several tens nanometers andnear-field light 115 is generated at the very small aperture 112 byintroducing the laser beam 118.

An information recording medium 113 is constructed by a two layerstructure of a light transmitting layer 119 comprising a lighttransmitting member and a light reflecting layer 120 comprising a lightreflecting member and a data mark 114 is formed on the lighttransmitting layer 119.

The propagated light 121 generated from the light emitting elements 116and 117 transmits through the light transmitting layer 119, reflected bythe surface of the light reflecting layer 120 and is irradiated to thedata mark 114. The data mark is constituted by a phase change material acrystal state of which is changed by being provided with energy. Outputlevels of the light emitting elements 116 and 117 are set such that thepropagated light 121 provides energy at a level which is slightlysmaller than a threshold of energy necessary for changing the crystalstate. Under the state, by irradiating the near-field light from thevery small aperture 112 to the data mark, the data mark receives energyexceeding the above-described threshold. Thereby, the crystal state ischanged and recording of information is realized.

The characteristic of the embodiment resides in that assist light forassisting near-field light for providing energy necessary for recordinginformation, is provided with a sufficient propagation space by thepresence of the light transmitting layer 119. Although the lower face ofthe planer probe 111 and the surface of the information recording medium113 are extremely proximate to each other and propagated light isdifficult to invade therebetween, by presence of the light transmittinglayer 119, assist light having a sufficient intensity can reach the datamark.

As has been explained above, according to the information recording andreproducing apparatus according to Embodiment 10, the data mark ispreviously irradiated with the assist light having sufficient intensityand accordingly, even by irradiating very weak near-field light in ashort period of time, the change in the crystal state of the surface ofthe information recording medium is caused and information can berecorded at high speed.

Industrial Applicability

As has been explained above, according to the invention, the firstinformation recording medium comprises the two layer structure of thelight transmitting layer comprising the light transmitting member andthe light reflecting layer comprising the light reflecting member andthe data mark is formed above the light reflecting layer andaccordingly, there is achieved an effect that the propagated lightgenerated by the interaction between the near-field light and the datamark can be reflected by the light reflecting layer via the lighttransmitting layer and can be emitted from the surface of theinformation recording medium and a sufficiently large amount of thepropagated light can be provided at the surface of the informationrecording medium at a position remote from the data mark.

Further, according to the invention, the second information recordingmedium comprises the two layer structure of the light transmitting layercomprising the light transmitting member and the light reflecting layercomprising the light reflecting member, the interface between the lighttransmitting layer and the light reflecting layer is inclined in onedirection, the data mark is formed on the light transmitting layer andaccordingly, there is achieved an effect that the propagated lightgenerated by the interaction between the near-field light and the datamark can be strongly reflected in the one direction at the lightreflecting layer via the light transmitting layer and can be emittedfrom the surface of the light recording medium and a sufficient amountof the propagated light can be provided at the surface of theinformation recording medium at a position remote from the data mark onthe side of the inclined face of the light reflecting layer 1.

Further, according to the invention, the third information recordingmedium comprises the two layer structure of the light transmitting layercomprising the light transmitting member and the light reflecting layercomprising the light reflecting member, the surface of light reflectinglayer is formed in the shape achieving reflection of light to thespecific area, the data mark 4 is formed on the light transmitting layerand accordingly, there is achieved an effect that the propagated lightgenerated by the interaction between the near-field light and the datamark, can pass the light transmitting layer, can be strongly reflectedto the specific area at the light reflecting layer, can be emitted fromthe surface of the information recording medium and a sufficient amountof the propagated light can be provided at the specific area at aposition remote from the data mark.

Further, according to the invention, the fourth information recordingmedium comprises the two layer structure of the light transmitting layercomprising the light transmitting member and the light reflecting layercomprising the light reflecting member, the diffraction grating isformed at the surface of the light reflecting layer, the data mark isformed on the light transmitting layer and accordingly, there isachieved an effect that the propagated light generated by theinteraction of the near-field light and the data mark can pass throughthe light transmitting layer, can be strongly reflected to the specificarea determined by the diffraction grating at the light reflecting layerand can be emitted from the surface of the information recording mediumand a sufficient amount of the propagated light can be provided at thespecific area at a position remote from the data mark.

Further, according to the first information reproducing apparatusaccording to the invention, there is used the information recordingmedium comprising the two layer structure of the light transmittinglayer comprising the light transmitting member and the light reflectinglayer comprising the light reflecting member and formed with the datamark on the light reflecting layer, the propagated light provided by theinformation recording medium is received by the light detecting means, areproduced signal having sufficiently large intensity indicatingpresence or absence of the data mark can be provided and accordingly,there is achieved an effect that there can be realized downsizedformation of the apparatus in the case of adopting the illumination modeand a transmission mode constituting a system of informationreproduction utilizing near-field light and there can be reproducedstable information having high reliability by the reproduced signalhaving the sufficiently large intensity.

Further, according to the second information reproducing apparatusaccording to the invention, there is used the information recordingmedium comprising the two layer structure of the light transmittinglayer comprising the light transmitting member and the light reflectinglayer comprising the light reflecting member and formed with the datamark above the light reflecting layer, the propagated light provided bythe information recording medium is received by the light detectingmeans, a reproduced signal having a sufficiently large intensityindicating presence or absence of the data mark can be provided andaccordingly, there is achieved an effect that there can be realizeddownsized formation of the apparatus in the case of adopting thecollection mode and the transmission mode constituting the system ofinformation reproduction utilizing near-field light and there can bereproduced stable information having high reliability by the reproducedsignal having the sufficiently large intensity.

Further, according to the third information reproducing apparatusaccording to the invention, there is used the information recordingmedium comprising the two layer structure of the light transmittinglayer comprising the light transmitting member and the light reflectinglayer comprising the light reflecting member and formed with the datamark above the light reflecting layer, the propagated light provided bythe information recording medium can be detected in two directionrelative to the very small aperture of the reproducing probe and therecan be carried out tracking control of the reproducing probe by thedifference between the detected two detected signals. Further, thenear-field light generated at the very small aperture of the reproducingprobe is utilized as a signal for tracking control and therefore, thereis achieved an effect that there can be carried out the tracking controlhaving high accuracy with high positional resolution.

Further, according to the fourth information reproducing apparatusaccording to the invention, as the reproducing probe, there is adoptedthe planer probe provided with the light detecting means or the lightirradiating means and accordingly, further compact apparatusconstitution is achieved. Further, the planer probe can be fabricated byusing the semiconductor fabrication technology and accordingly, there isachieved an effect that mass production having high reproducibility canbe carried out.

Further, according to the fifth information reproducing apparatusaccording to the invention, the propagated light provided by theinformation recording medium comprising the two layer structure of thelight transmitting layer and the light reflecting layer, is received bythe light detecting means of the planer probe arranged to incline suchthat the clearance between the planer probe and the surface of theinformation recording medium becomes sufficiently large, there can beprovided the reproduced signal having sufficiently large intensityindicating presence or absence of the data mark and accordingly, thereis achieved an effect that there is realized downsized formation of theapparatus in the case of adopting the transmission mode constituting oneof the systems of information reproduction utilizing near-field light,further, there can be reproduced stable information having highreliability by the reproduce signal having the sufficiently largeintensity.

Further, according to the sixth information reproducing apparatusaccording to the invention, as the reproducing probe there can beutilized the probe of the optical fiber type used in a conventionalnear-field microscope and accordingly, there is achieved an effect thataccumulated technology of the near-field microscope is effectivelyapplicable to the information reproducing apparatus.

Further, according to the seventh information reproducing apparatusaccording to the invention, as the reproducing probe there can beutilized the probe of the cantilever type used in a conventionalnear-field microscope and accordingly, there is achieved an effect thataccumulated technology of the near-field microscope is effectivelyapplicable to the information reproducing apparatus.

Further, according to the first information recording and reproducingapparatus according to the invention, in an information recording andreproducing apparatus in which a recording and reproducing probeprovided with a very small aperture for generating near-field lightrecords and reproduces information to and from an information recordingmedium by carrying out an interaction between the recording andreproducing probe and the information recording medium via thenear-field light wherein the information recording medium comprises atwo layer structure of a light transmitting layer for transmitting lightand a light reflecting layer for reflecting light and formed with a datamark constituting a unit of the information on the light transmittinglayer, the information recording and reproducing apparatus comprisingnear-field light generating light irradiating means for irradiatingirradiation light for generating the near-field light to the recordingand reproducing probe, and propagated light irradiating means forirradiating light to the light reflecting layer such that the light isirradiated to an area at which the near-field light on the lighttransmitting layer carries out the interaction and accordingly, there isachieved an effect that the data mark can be irradiated not only by thenear-field light from the probe but also by the light from the lightreflecting layer and larger energy can be provided by the data mark.

Further, according to the second information recording and reproducingapparatus according to the invention in accordance with the firstinformation recording and reproducing apparatus according to theinvention, is characterized in that the light irradiated to the lightreflecting layer is provided with an intensity and a wavelength forassisting the near-field light for recording the information andaccordingly, there is achieved an effect that energy necessary forinformation recording can be provided not only by the near-field lightfrom the probe but also by the assist light from the light reflectinglayer and recording having high reliability at high speed can berealized by changing the state of the surface of the informationrecording medium by controlling the very weak near-field light.

Further, in the first and the second information recording andreproducing apparatus according to the invention, by carrying out theinvention similar to any invention of the fourth through the seventhinformation reproducing apparatus according to the invention, inaddition to inherent effects of the first and the second informationrecording and reproducing apparatus according to the invention,respective effects of the fourth through the seventh informationreproducing apparatus according to the invention are realized.

What is claimed is:
 1. An information recording medium comprising: adouble-layer structure comprised of a light transmitting layer fortransmitting light and a light reflecting layer for reflecting light,the light transmitting layer having a data mark which comprises a unitof information that is reproduced when light irradiated to the data markgenerates propagation light that is reflected by the light reflectinglayer at an interface between the light transmitting layer and the lightreflecting layer.
 2. An information recording medium according to claim1; wherein the interface between the light transmitting layer and thelight reflecting layer is inclined in one direction.
 3. An informationrecording medium according to claim 1; wherein the light reflectinglayer has a surface disposed at the interface between the lighttransmitting layer and the light reflecting layer for reflecting thepropagation light.
 4. An information recording medium according to claim3; further comprising a diffraction grating disposed at the interfacebetween the light transmitting layer and the light reflecting layer. 5.An information recording medium comprising: a double-layer structurecomprised of a light transmitting layer for transmitting light and alight reflecting layer having a data mark which comprises a unit ofinformation that is reproduced, the light reflecting layer underlyingthe light transmitting layer so that propagation light produced by aninteraction between near-field light which interacts with the data marktravels an optical path by which it passes through the lighttransmitting layer, is reflected only once by the light reflectinglayer, passes again through the light transmitting layer and emergesfrom the double-layer structure of the information recording medium. 6.An information recording medium according to claim 5; wherein a distanceof the optical path traveled by the propagation light is twice or morethan a thickness of the light transmitting layer.
 7. An informationrecording medium according to claims 5; wherein the light reflectinglayer has a surface disposed at an interface between the lighttransmitting layer and the light reflecting layer for reflecting thepropagation light, the surface being inclined in one direction.
 8. Aninformation recording medium according to claim 5; wherein the lightreflecting layer has a surface disposed at an interface between thelight transmitting layer and the light reflecting layer for reflectingthe propagation light, the surface having two recessed portions.
 9. Aninformation recording medium according to claim 8; wherein the tworecessed portions are symmetrical about an axis passing through the datamark.
 10. An information recording medium according to claim 5; furthercomprising a diffraction grating disposed at an interface between thelight transmitting layer and the light reflecting layer for reflectingthe propagation light.
 11. An information reproducing apparatuscomprising: an information recording medium comprised of a double-layerstructure having a light transmitting layer for transmitting light and alight reflecting layer for reflecting light, the light transmittinglayer having a data mark which comprises a unit of information that isreproduced by an interaction between near-field light and the data markso that the data mark generates propagated light that is reflected bythe light reflecting layer; a probe for generating the near-field lightat a fine aperture thereof; and light detecting means for detecting thepropagated light generated by the interaction between the near-fieldlight generated by the probe and the data mark of the light transmittinglayer and reflected by the light transmitting layer for outputting adetection signal corresponding to the detected propagated light.
 12. Aninformation reproducing apparatus according to claim 11; wherein thelight reflecting layer has a surface disposed at an interface betweenthe light transmitting layer and the light reflecting layer forreflecting the propagation light, the surface being inclined in onedirection.
 13. An information reproducing apparatus according to claim11; wherein the probe comprises a generally planar-shaped substratehaving a hole in a shape of an inverse cone, an end of the hole havingthe fine aperture; and wherein the light detecting means is disposed onthe substrate.
 14. An information reproducing apparatus according toclaim 13; wherein the probe is inclined relative to a surface of theinformation recording medium.
 15. An information reproducing apparatusaccording to claim 11; wherein the probe comprises an optical fiberhaving the fine aperture at a front end thereof.
 16. An informationreproducing apparatus according to claim 11, wherein the probe comprisesa cantilever-type probe having the fine aperture at a projected portionthereof.
 17. An information reproducing apparatus comprising: aninformation recording medium comprised of a double-layer structurehaving a light transmitting layer for transmitting light and a lightreflecting layer for reflecting light, the light transmitting layerhaving a data mark which comprises a unit of information that isreproduced by an interaction between near-field light and the data markso that the data mark generates propagated light that is reflected bythe light reflecting layer; a probe for generating the near-field lightat a fine aperture thereof; first and second light detecting meansdisposed on opposite sides of the fine aperture of the probe fordetecting the propagated light generated by the interaction between thenear-field light generated by the probe and the data mark of the lighttransmitting layer and reflected by the light transmitting layer and foroutputting first and second detecting signals, respectively,corresponding to the detected propagated light; difference calculatingmeans for calculating a difference between the first detecting signaloutputted from the first light detecting means and the second detectingsignal outputted from the second light detecting means and foroutputting a signal corresponding to the calculated difference betweenthe first and second detecting signals; position controlling means forcontrolling a position of the probe in accordance with the signaloutputted from the difference calculating means; and reproduced signalgenerating means for generating a reproduced signal by adding the firstdetection signal to the second detection signal.
 18. An informationreproducing apparatus according to claim 17; wherein the lightreflecting layer has a surface disposed at an interface between thelight transmitting layer and the light reflecting layer for reflectingthe propagation light, the surface being inclined in one direction. 19.An information reproducing apparatus according to claim 17; wherein theprobe comprises a generally planar-shaped substrate having a hole in ashape of an inverse cone, an end of the hole having the fine aperture;and wherein the first and second light detecting means are disposed onthe substrate.
 20. An information reproducing apparatus according toclaim 19; wherein the probe is inclined relative to a surface of theinformation recording medium.
 21. An information reproducing apparatusaccording to claim 17; wherein the probe comprises an optical fiberhaving the fine aperture at a front end thereof.
 22. An informationreproducing apparatus according to claim 17; wherein the probe comprisesa cantilever-type probe having the fine aperture at a projected portionthereof.
 23. An information recording and reproducing apparatuscomprising: an information recording medium comprised of a double-layerstructure having a light transmitting layer for transmitting light and alight reflecting layer for reflecting light, the light reflecting layerhaving a data mark which comprises a unit of information to bereproduced; a probe for generating near-field light at a fine aperturethereof and for recording information on and reproducing informationfrom the information recording medium by an interaction between thenear-field light and the data mark of the light reflecting layer; firstlight irradiating means for irradiating irradiation light to generatethe near-field light at the fine aperture of the probe; and second lightirradiating means for irradiating light to the light reflecting layer sothat the light is irradiated to the data mark of the light reflectinglayer.
 24. An information recording and reproducing apparatus accordingto claim 23; wherein the light irradiated by the second lightirradiating means comprises assist light having preselected intensityand wavelength for assisting the near-field light to record theinformation.
 25. An information reproducing apparatus comprising: aninformation recording medium having a light transmitting layer fortransmitting light and a light reflecting layer for reflecting light,the light transmitting layer having a data mark which comprises a unitof information that is reproduced by an interaction between near-fieldlight and the data mark so that the data mark generates propagated lightthat is reflected by the light reflecting layer; a probe having a fineaperture; light irradiating means for irradiating light through the fineaperture of the probe to generate the near-field light which interactswith the data mark of the light transmitting layer of the informationrecording medium to thereby produce the propagation light which travelsan optical path by which it passes through the light transmitting layer,is reflected by the light reflecting layer, passes again through thelight transmitting layer and emerges from the information recordingmedium; and light detecting means for detecting the propagation lightand for producing a reproduced signal corresponding to the unit ofinformation represented by the data mark of the light transmittinglayer.
 26. An information reproducing apparatus according to claim 25;wherein a distance of the optical path traveled by the propagation lightis twice or more than a thickness of the light transmitting layer of theinformation recording medium.
 27. An information reproducing apparatusaccording to claim 25; wherein the light reflecting layer has a surfacedisposed at an interface between the light transmitting layer and thelight reflecting layer for reflecting the propagation light, the surfacebeing inclined in one direction.
 28. An information recording andreproducing apparatus comprising: an information recording medium havinga light transmitting layer for transmitting light and a light reflectinglayer for reflecting light, the light transmitting layer having a datamark which comprises a unit of information that is reproduced by aninteraction between near-field light and the data mark so that the datamark generates propagated light that is reflected by the lightreflecting layer; a probe having a fine aperture; light irradiatingmeans for irradiating light through the fine aperture of the probe togenerate the near-field light which interacts with the data mark of thelight transmitting layer of the information recording medium to therebyproduce the propagation light; light detecting means for detecting thepropagation light and for producing a reproduced signal corresponding tothe unit of information represented by the data mark of the lighttransmitting layer; and means for directing the propagation light to thedata mark of the light transmitting layer.
 29. An information recordingand reproducing apparatus according to claim 28; wherein the lightreflecting layer has a surface disposed at an interface between thelight transmitting layer and the light reflecting layer for reflectingthe propagation light, the surface being inclined in one direction.